Telephonic transmitter.



P. STRAGLUT'II.

TBLEPHomo TRANSMITTER.

APPLICATION I'XLED AUO.l1. 1008.

955,71@ Patented Apr. 19,1810.

uw Pim. IE.. LIM.. MINM. D C

lP. armamm. TLEYBOHU TRAB'ITTER.

I PLOTO FILED U. ll, 190.- 955,?1 Apr. 1n. 1am

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P. BTBAGIO'KTL TBLIWHOHIU TBLKBNITTM.

APPILWAI'IOI "LED AUG. Il. lw. @65316. l www Apr. 19, ww.

4 IIIITHIIBR E.

mu rannlnciuno mummn c3.

T?. STRAGITTL ITELBPHOHIO TRANSMITTER.

urmonxol num umn, nos.

956,316. rammed Apg. 19,11*@1'0.

6 BEBKHEIBE? C.

. /06 gj J6 /06 /49 M 7 @L mf titi PIITRO BTIAGIOTTI. 0F HUBLEY, WISCONSIN TELEPHONIC TBANBKITTEB.

Speottcatlon o! Letten Bat/amt.

Patented Apr. 1o, 191e.

Applimtion died August 11, 1908. Serial lo. 448,028.

To all whom 'it may concern:

De it linown that I, llis'i'iio S'rn/ioioi'ri, subject of the King of italy, residing at llurluy, in the county of iron and State of iVisconsin, have. invented Cci'taininw and useful iiiipiawcnicnts in 'llelcphonic 'lrans-- inittcis: and I do declaro the followinigto lic a full, clear, and exact desci'i )tion olf the invention, such as will enable ot ici's skilled in the art to which it ap )crtains to make and use the same, reference fing had to the accompanying drawings, and to the figures of reference marked therooinwhich formapart of this specification.

M v invention relates to the class of telephony, but more partic'iilai'ly to a 'differential telephonie transmitter; aud my invention :ousists in thc construction of thcl ditierential micro-phone ariaiwed so that equality of pressure is obtained in its two parts.

My invention further consists in coni-itruct-` ing the whole apparatus in such manner that it may turn around an axis, so that no straiiii may initially act on the central electra. e.

My invention further consists in arranging a disk or diaphragm of felt in front of thel miam-phone to prevent troubling interferences through the air.

My invention further consists in the construction of the micro-phone, and in the wa of arraiv ing its several elements in su manncr t iat the diaphragm of the microphone is more vlas-tit: than the usual elastic dia liragai.

B y invention further consists in the construction of the micro-phone, which not only allows its rotation around the axis to rei'cnt all initial strain on the central ecctmde of the micro-phone, hut also allows the micro-phone to oecillate nynchronically with the central electrode.

My invention fui-ther toiisists in certain other noi'cl details of construction and in combinations of parte, all of which will be first fully described und afterward spccically' pointed out in the appendedclaims.

eferi-ing to thc. accompanying drawings: Figui-c 1 is a vertical sectional vicw through the transmittcr. Fig. 2 is a horizontal sectional view thmngh thc transmitter. Fig. Il is an elevation lookin v forward, this back plate bein" rcuiovcd. iFig. 4 is an elevation of the haci( plate. Fig. 5 is an elevation of one of the supporting arms or plates. Fig.

plied to or plates and casing for the micro-phones.

6 is n top plan of the two supporting arms Fig. 7 is an edge view of the casingof the i micro-phones. g. 8 is a perspective view of the insulating ring within the casing, and of the miem-phones. Fig. 9 is an elevation of the transmitter showing a slight modification. Fig. 10 is a horizontal section .through the saine. Fig. 11 is a fragmentary view of a part of the supporting arms or plates of the micro-phone and the axis therefor. Fig. 12 is a plan view of a sli ht moditicatioiiof the supporting arms or p stes for the microphones. Fi 13 is anV elevation of the s i'ingsholing the supporting arms or p ates of the micro-phones. Fig. 14 is a'. plan of a slight modification ofthe microphones. Fig. 15 illustrates a slight modification of the supporting arms or plates .of

the micro-phones. Fig. 16 is a. rear elevation ot the transmitter illustrated 'in 9. Fig. 17 is a. detail view of the axis o the supportin arms of the micro-phone as aplgs. 14 and 115.l

Like numerals of reference indicate the same parts throughout the several figures in which;

1 indicates the di'erential tele honio transmit r which oom rises a fron plate 2 to'whi is secured e usasl mouth ieee B. Connected to the frontal plate by means of screws i is a ring said ring heing provided with an annular off-set .6, between which oK-set 6 and the frontal dplate 2 the' diaph I is held. Snrroundin diaphragm is t t) indicates the 'dilerential micro-phone 'whicheomprisel` a micro-phone 10 and a micro-phone 11.

12 and 18 indicate the supportii arms or pilates of the two microong and 11.

e su arm or te ing provided I:Vith :small pla. 'of ver hard and well smoothed carbon 14, while ie supporting arm or plate 18 is provided with a similar late 15.

1 indicates the centra ential microphone, said late of the dition ate being of metal and bei covered on h aides with sheets of smoot carbon 17 and 18, layers of wdered carbon 19 and 20 bein inter between the carbon plates as theY a U-lhaped insulating rin,o 8.

early shown in ilo the in'icio-phoiieiis arranged an insulating.: ring 21. said insulatiiig-:iijigflieingi made of two parts .22 aiu 22) which nieet :it the points 2l and 25. Portions of t'lit`riiig.2l nre. cut' awa; at '2G and leaving a nai-row strip 28 as 'liowiii iniFigs. i2 and "Iwo openings or perorations 29 and 30 are" provided in the ring '21. said openings or perforations occuriiie at ilie breaks 2l and Q5 iii the ring y l as clearly shown in Fig. 8.

lReferring to'lfigs. 1 and t2 it will be seen that the supporting arm or plate 1'2 is coi'- ered with a layer of softl tissue 3l foisthe purpose of extinguishing the sound waves which might disturb the microplioiiesor cause them to actl with less exact ness.

Referring i'iow to Fig. 1 it will be seen. 'that two stems 3'?. and 2334 pass through the pei'forations :'29 and 30 in the insulating ring :'21, said stems being connected to the central plate 16 of the micro-phones; and it will also be seen that the stems-Z and 33 meet at tlic point 34 where they form a steui 35.-s:iid stein assing through and being connected to tlie diaphragm 7 as clearly shown in Figs. 1 and 2.

Referring non' to Fig. 3 it will be seen that two supports 36 und 3T ure carried onA the ring 5, which ring is secured to the frontal plate '2,' and two screws B8 and 39 are carried in saidsupports 36 and 37, the eiids of said screws 3S and 39 being7 cony cared iii order to receive .the pivot or axis 40. aid pivot or axis 40 is preferablv square-iii [cross section as shown in Fig. sliaip pointed at its ends while the supporting arius or plates 1L. and 13 of the micro-Y phonesnre formed with elbows 4L and 4:2 to eiiibriice thesaid pivot or axis-l0 as clearly shown in Fig. 2, .said pivot or axis l0 and thc two su )porting arms or lates l. and 13 beiii'finsii ated fionil e'acli otliei' by means of siiittible insulating material 43 as shown in 9. Securing the twoarnis or plates 11 and 12 togetlierarel'two screws 44 and 45, said screws forming an electrical connection 'with the sup ioi'tiiig arm or plate 12 and being insulated from the supportingr ariii or plate 125 by suitable insulating?y material as clcai'liwsliow'ii in Fig. 46 indicates the rear plate of the tran-.inittcr` l'i i1li,as shown in Figs. 1 and 2,' is held in position by means ot the four screws 19. The casing oi.' cover li" is secured to the frontal plate '2 und to the rear plate 46 bv means of suitable screws 48, the rea'i'yinetallic cap or cover 50 for the transmitter passing over tliei'eai' edge of tlie'czising 4T and beingr secured ilicrcto and to thea-car plate 1Q by .means of suitable screws-18.

iet'errine now to Fig. 4, which illustrates the i'efii' plaieltt in elevation it will be seen thai the saaie is prov'iiled with :in oblong opening 5l through which. the wires ot esami@ :if-"ei ',"1' ,-'i fliottralidilttrpass. ititalile adjustin screw 52 is also carried in said plate 46, sai screw entering-a nut 53,'said 4nut operutin r within the slot 54 formed iii the. plate 46. i

fgroove 55 is formed in said nut. 53, said groove bein(Y stems 56 and sa (rig, 3).

Referring now to Figs. 1 and 3 it will be seen that two supporting ieces 60 and 61 passl from the ring 5 to t e rear late 46, cach of Said pieces being provide with a yoke 69., within which yokes the adjusting arms 58 and 59 are pivoted by means of bolts 63. The said adjusting arms 58 and 59 as will a pear from Figj are'provided on their ree ends with a layer of soft insulating material 64, said free ends of the adjusting arnis 58 and 59 engaging the su porting arms or plates 12 and 13 of tile micro-phones as clear] shown in Fig. 3.

Referrin now to liigs. 1 and 2 it will be seen that t e rear c ap or cover 50 of the transmitter is provided with two slides which are adapted to operate within the slide 66 for the pur of allowing the transmitter to be raise or lowered.

Referring new to Fig. 2 it will be seen that a small arm 67 connects with the diaphragm 7 to which arm a wire 68 is connected. It will also be seen that the lsupporting arm or plate 12 is connected to the wire 69 through for the puppose of receiving the 57 of the a jusfing arms 58 and the medium of the screw 44, while the su porting arm or plate 13 is connected to t e wire 7 at the point 71.

Referring now to the Figs 6,7 and8 it will be seen that a cover or retaining piece 72 is secured to the end of the supporting arms or plates 1Q and 13, said cover or retaining piece 72 i for the purpose of retaining the powderii carbon within the microphones as well as to keep the ring 21 in place.

Referring now to Figs. 9. 10 and .16 which illustrate a slight modification of the transmitter, it will be seen that a small metal disk 'i' 5 is rovided within the frontal plate 2, said disli 75 having a rim or @ange 76 secured to tlie edge of said disk, said rim or flange 76 being concaved as clearly shown in Fig. 10, said rim or flange being secured to a nietal ring 77 and insulate vfrom the frontal plate 2 by means of a strip of insulating material 78. V

As shown in Fig. 10 a tiange on the inner surface of the frontal plate 2. said thinge 79 carrying a disk of soft felt tissue 80, said disk-being bound bj.' a U- sliaped rim 81 which is tixed to the thinge TJ by means of suitable'screws 82. indicates the differential niicio-plxioiie which comprises a micro-phone 8,1. and micro-phone S5; and as shown in `Fig. 10 two siippoi'tiiij r arms S6 und 87 ni'e provided forlioliling 'lie microphones. '.l`he Ciitl'eiential micro-phone comprises two central electrodes SS and 89, each l i l 'its .tmdee88and89 in 9 a'stem 98 connected to the disk 75 p through the felt disk 80and is connected to the thin steel plate 95l at .the point 99 (Fig. 16); and referring to Figs. 9, 10 and 16 it will be seen that the'screw 92 which connects` the stems of thecan se throu h the) stems o l elecidv steel plate 95,.the sai the said elec tiodes firinl said late se clearly shown in 1g.. 1 and 01 in'dicatethe outer electrodes of `the two micro-phon said electmdes' 100 and'101 being provide with stems102 and 108, said stems entering the'supirting arms 86 and 87 and secure therein y means of screws 104. The oen. tral electrodes 88 and 89 and the outer elec,- trodes 100 'and 101 are covered with plates of 105, and the intervening spac betw'oeinlthe feo of smooth carbon arellled .with granulated carbon 106. Surroun the electrodes of b oth microphones iti inculati material l107 -and coverin each el e is a' casing 108 and a cap 09, said electrodes bein insulated from said and cap as early shown in Fi eferring now to Fig. 11 it will be seen trodes on t that two supports 110 and lllprovlded with screws 112 and 118 ca the axis or-pivot 114, which axis or pivot is preferably square in cross section, and as will appear from Fig. 10 the supporting arms 86 and87 of the-microhones are provided/'with elbows 115 to con orni to theshape o; the axis or pniv'ot 114, said sup rtin arms being insuted from each ot er an from the axis or pivot 114 by'a strip of insulatii material 116` |117 indicates a holt wh ch passes through the su portin; r arms 86 ind 87 securel insulated) therefrom, said bolt being for e pur of adjusting the said arms and for adlusting the pressure of the elecmicro-phones I t As ia shown in Figs. 9 land 10 two springs 118 and 119 commanded by an adjusting screw 120 engage the su porting arms 8G and 87 and are insulated ticrefroiii by insuhiting material 121 as clearly shown in Fig. 10. The late 95 is provided with an extension 12g to which the electric conductor 123 is connected, and the current from here comes to the two faces of the central electrodes 88 and 89, thence forking, the current passes tiiougli each micro-phone 84 and. 85

e granulated carbon within the' ,86 and 87.

to the points i12-l and 125 connected to the :supporting ai'i'ns 8G and 87 as shown in l-`ifs. 9 and 1t.. d

{efei'i'ing now to Fig. l2, which illustrates n modification of the supporting arms I 86 and 87, it will be seen that an adjusting sei-ew 126 is provided in order to regulate the pressure of the carbon within the micro phones. In order to ve'to the transmitter a slightly bent position such as is usually v5 given by the usual support of transmitters, and to secure more stability of the support ing arms 86 and 87 the two springs 118 and 119-ivhich hold the apparatus are in this construction somewhat shorter than in the construction shown in Figs. 9, 10 and 11.

Referring now to Fig. 1l it will be seen that in place of the micro-phones illustrated in Figs. 9 and 10 I iiiay employ the two su ,poi'tin arms 89 and 87 n'iuch smaller, an I provi e on the faces of said arnisvsinooth carbon plates 127 and 128, while on the steel plate 95 I secure a sphere of platinum 129.

In the construction illustrated in Fig. 15 I employ the supporting arms 8G and 87 extremely thin and frail and connect the free ends to ther b nicans of u boltlBO which is siiitallyinsu ated froml the arins.

When employing .the construction as shown in Figs. 14 and 15 the form of axis is employed as shown in Fig. 17, the pivot or axis 114 being integral .vitli the screw 131 which passes through the supporting arms Hsving'fully described the several parts of my invention its operation is as follows:

In the construction illustrated in Figs. 1 and; 2 the whole niicro phone niay turn around the axis 40, and if the axis be vertical the whole system is in such a condition that 'no initial or constructory strain may perinanently be found between the small central late 16 and the balance of the niiciolioness. The plate 16 is in this way perfectly flreeand the two parts of the diticrential micro-phone will be exactly in the saine condition. To better put the two parts of the micro-phone iii-equal condition-and 'for the exact centering of the small central plate lt'i the two )eripheries or openings 29 in the insulatin ring 21 are of4 great use, for b v this the snm central plate 16 mii be exactly placed in its rop'er osition, am furthermore the gramiljar car n may be 'easil introduced, the opening-for the carbon being afterward com ered up by the small retaining plates 7'2 as clearly shown in Fig. 2, und the screw 44 is intended to re ulate the pressure othe carbon to obtaint e inost satisfactory resistance, as the apparatus actsI better. ll'lien' the axis 40 is vertical the slides G5 are provided for inaintainin the transmitter in a vertical position. s, however, is sometimes necessary to move the transmitter about, the two adjusting arms 58 and 59 are provided which.

are movable about the axes 63, thus keeping the supporting arms of the micro-phone in position, said arms bein adjusted in the manner as above described.

5 The electrical distribution is as follows:

The current comes to the dia hragni 7 and is led through the stem 35 to t e central electrode 16, and as the inicro-phonic case is of insulating material the current goes through the carbon going to the two plates 12 and 13 from which it'is led out through the conductors B9 and 70 to .the transformers (not shown). The sound waves produced in front of the diaphragm causes it to vibrate, and

by the stem 35 the central electrode 16 is causedto vibrate, so that the electric resistbeoome alterna varying, and conseuently the c rent is alternately varied. o make the vibration of the central electrode 16 poible the stems 32 and 33 which hold it mustbe in condition to move freely in the holes or. openings 29 and 30 in the ance of the tlafiarts of the micro-phone insulating ring 22, through which holes the 5 said stoms pass, and as it is necessary to maintain the granular carbon within the micro- `hone two small felt collars are rovi as shown in Fi 1, which collars while giving a ve sl' t resistance to the 0 vibration) are su cient to maintain the granular carbon within the micro-phones.

Referring to the construction shown in Figs. 9, 10 and 16, the two arms 86 and 87 bein supported on the axis 114 allow the 5 whoe 'system to oscillate, and whenthe micro-phones are fixed to the late 95 as shown in F' 10 pressure on t e nular carbon within the micro-phones is regulated by means of the screw 117 in order to 0 secure the greatest etliciency; as the amount of pressure is dependent upon the screw 117, by which the two external electrodes are adjusted while the exact similarity of. preseure in both inicrophonic chambers is de- 5 pendent onlyi upon the rotation around the axis 114. e an *le of rotation to obtain euch similarity wi be very small as it is necessary to avoid dis-similarity of strains; however it is none the less a rotation and D equilibrium is reached when the lever niomentuni of the' applied forcesI in support of said axis is aero. The applied forces here are thc pressures acting on the external electrodes which nro opposite to each other, and to have equilibrium they 'must be alike. vVhen the sound waves strike-on the disk or diaphragm 75 the plato 95 vibi'ates; the

central electrodes 88 und 89 are also ritirati-d.

rotatabie around the nxis114. The union 99 (Fig. tti) of thiI .stein 98, which is r'onnected to thel disk "Iii, causes the vibratory movement. of tho pluto. 95 to be increased :it the oint on which tlielccntral electrode of the. 'ferentinl micro-phono is fixed. ln the vibrations of thc contrat electrode the nres sure of thc granular cui-hon being "cry slight, und the mass of the whole system being relatively large in. comparison to the central vibrating part, this central vibrating, art muy be considered as ,freeldirvihrating ctwcen two immovable parts. 'lo het tei' maintain this iniinobility of the external electrodes the s )rings 118 and 11S) are prol vid'cd. By-closingr the springs 1.15 und 119 (Fig. 12) so that they cannot. leave the position of greatest sensibility tlie transmitter may be employed in any position like the usual transmitter in universal use.

(Referring to the construction shown in Figs. 9, 10 and 11.) .The sound waves striking the disk 75 easily displaccs said disk, while this displacement is increased on account of the compression on the inside ofthe concaved ringr or collar 76 because the coniprcssion from the inside of said ring or cotar tends to extend ttie surface of the. collar, so iis toin'crcase thc eti'cct .of the compression. On account of the felt disk 8() :irrnnod behind the disk 75 all Sound waves stri ing against the disk are absorbed.

In thv modification shown in Figs. 14 :ind l5 the reciprocal positioi between the tangential planes of thc carbon and the sphere will`not be altered, and if the arms 86 and 87 are'made of aluminum the whole mass of the micro-phone becomes so li ht that it can oscillate around its axis 11 harmonicall.7 with the oscillations of the :ate 95.

.Vhen iii the construction the. line o the contacts pz..-;sesthrough the conter of oscillation as compared to the rotation axis no force acting between the sphere and the carbon plates can be transmitted to the supports 112 and 113 of the axis; consequently the greatest sensibility and exactncss is obtained,

the wliolesystein being free of any vibra-4 tions from the said supports. ln this coinbiiuition the entire niicrwplioiie vibratcs ltollowing the conti-ul pluto 5);', without nui' eelt vibration, because no elastic force cin-tine.

use

liti

isoA

12.5 tht sphere 129 thvy screw 131isprovidcthainlf to avoid all dnnger of any -occusionul p:iit-,\ ing' of any of the parts which yniight cause. tutt` )honic troubles I can provide rybolt 130,.

iiown in Fig 15 which nbsoluteiyinaim.

. ist

esame steel and insulated electrically from' the arms.

Havin thus fully described my invention what I c aimas new and desire to secure by Letters Patent of the United States, is';

.1. A transmitter comprising a differential micro-phone comprising two separate micro phones', each of s aid separate micro-phones comprising two electrodes' arran in a casing of insulating material, an a layer of carbon dust a between each of said electrodel one electrode of each micro-phone bearings for the 'same to permit oscillations, the whole arranged in such manner' as to allow self adjustment of the external electrodes with respect to the central one.

l 2. A transmitter comprising a differential niicro-phone comprising three electrodes, a plate carryin the central electrode to which late sai central electrode is mechanica y connected, the two other electrodes being provided with ahard smooth surface,'a su port ca each of said last mentioned e ectrodes, sai support comprising two parts electrically separate' and mechanically connected to an axis external to the micro-phone, and bearings for the same to permit itto turn, to allow automatic adjustment of the said two other electrodes with respect to the central one.

3. A transmitter com rising'three electrodes, a plate carrying e central electrode of the three, an axis external to the microphone to which the two external electrodes are rigidly connected, and means for allowinf; said axis to turn on its bearings, to effect se f adjustment of the two external electrodes with respect to the central one.

4. A transmitter comprising a diii'erential micro-phone having three electrodes, a plate carrying the central electrode of the three, and means for holding the other two electrodes in such manner as to allow them under thc inl means for mechanically connecting Said diaphragm with the central electrode of the said thict.` electrodes., and means for holding the other two electrodes in such manner as to permit them to turn around an axis external to the microphone, to allow self adjustment with, respect to the central eleotrode.

6, A transmitter comprising a dilferential inicro-phone,haviiig three' electrodes, a dia-- hragm adapted to vibrate' under the inuence of the sound waves; a flange or collar on said diaphra ,the exterior surface of said. flange or co lar being concaved, means for mechanical] connecting said'dia h with the centra electrode of the said three electrodes, arid means forholding the other two electrodes in auchl manner as to permit them to turn on an axis external to 'the microphone.

7. A transmitter comprising a differentialmicro-phone having three electrodes, a. late carryin the central electrode of the t ree, means or holding the other twoelectrodeo i'n such manner as to rmit them to turn around an axis externalxio the micro-phone a-diaphragm, and a-disk of soft material-sg distinct and separate from the vibrating parts and interposed between said diaphil'igm and said micro-phone as an acoustic wa 8. A transmitter comprising a-dierenti'al.

micro-phone having .three electrodes, adiaphra mechanica ly connected to the ciniti-al e ectrode 'of the three, a suport for the other two electrodes, an axis r the two outer electrodes external to the micro-phone, said support mechanically connecting the two outer electrodes with said axis,'beariings for-said axis, said axis being permitted to turn on its bearings, and means on said suppflilrt for regulating the pressure in the microone. p 9. A transmitter comprising a differential microphone havin three electrodes, a,dia 4 phragm mechanica y connected to the central electrode of the three, a sup rt foi' the other two, an axis for the otnertwo :lcctrodes external to the microphone, 'said support mechanically connecting the other twr electrodes to said axisLbearings u n which said axis is permitted to turn to a ow self adjustment of the 'external electrodes w'ith respect to the central one, and means- PIETRO STRAGIOTTI.

Titncsscs C. M. Foitaas'i', C. llCGii Dui-ft' 

